Global InformationTransition metal dichalcogenide monolayers information
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Transition-metal dichalcogenide (TMD or TMDC) monolayers are atomically thin semiconductors of the type MX2, with M a transition-metal atom (Mo, W, etc.) and X a chalcogen atom (S, Se, or Te). One layer of M atoms is sandwiched between two layers of X atoms. They are part of the large family of so-called 2D materials, named so to emphasize their extraordinary thinness. For example, a MoS2 monolayer is only 6.5 Å thick. The key feature of these materials is the interaction of large atoms in the 2D structure as compared with first-row transition-metal dichalcogenides, e.g., WTe2 exhibits anomalous giant magnetoresistance and superconductivity.[1]
The discovery of graphene shows how new physical properties emerge when a bulk crystal of macroscopic dimensions is thinned down to one atomic layer. Like graphite, TMD bulk crystals are formed of monolayers bound to each other by van-der-Waals attraction. TMD monolayers have properties that are distinctly different from those of the semimetal graphene:
- TMD monolayers MoS2, WS2, MoSe2, WSe2, MoTe2 have a direct band gap, and can be used in electronics as transistors and in optics as emitters and detectors.[2][3][4][5]
- The TMD monolayer crystal structure has no inversion center, which allows to access a new degree of freedom of charge carriers, namely the k-valley index, and to open up a new field of physics: valleytronics[6][7][8][9]
- The strong spin–orbit coupling in TMD monolayers leads to a spin–orbit splitting[10] of hundreds meV in the valence band and a few meV in the conduction band, which allows control of the electron spin by tuning the excitation laser photon energy and handedness.[11]
- 2D nature and high spin–orbit coupling in TMD layers can be used as promising materials for spintronic applications.[12][13]
The work on TMD monolayers is an emerging research and development field since the discovery of the direct bandgap[2] and the potential applications in electronics [14][3] and valley physics.[7][8][9] TMDs are often combined with other 2D materials like graphene and hexagonal boron nitride to make van der Waals heterostructures. These heterostructures need to be optimized to be possibly used as building blocks for many different devices such as transistors, solar cells, LEDs, photodetectors, fuel cells, photocatalytic and sensing devices. Some of these devices are already used in everyday life and can become smaller, cheaper and more efficient by using TMD monolayers.[15][16]
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- ^ a b Splendiani, A.; Sun, L.; Zhang, Y.; Li, T.; Kim, J.; Chim, C. Y.; Galli, G.; Wang, F. (2010). "Emerging Photoluminescence in Monolayer MoS2". Nano Letters. 10 (4): 1271–5. Bibcode:2010NanoL..10.1271S. doi:10.1021/nl903868w. PMID 20229981.
- ^ a b Radisavljevic, B.; Radenovic, A.; Brivio, J.; Giacometti, V.; Kis, A. (2011). "Single-layer MoS2 transistors". Nature Nanotechnology. 6 (3): 147–50. Bibcode:2011NatNa...6..147R. doi:10.1038/nnano.2010.279. PMID 21278752.
- ^ Sundaram, R. S.; Engel, M.; Lombardo, A.; Krupke, R.; Ferrari, A. C.; Avouris, Ph; Steiner, M. (2013). "Electroluminescence in Single Layer MoS2". Nano Letters. 13 (4): 1416–1421. arXiv:1211.4311. Bibcode:2013NanoL..13.1416S. doi:10.1021/nl400516a. PMID 23514373. S2CID 207581247.
- ^ Lopez-Sanchez, O.; Lembke, D.; Kayci, M.; Radenovic, A.; Kis, A. (2013). "Ultrasensitive photodetectors based on monolayer MoS2". Nature Nanotechnology. 8 (7): 497–501. Bibcode:2013NatNa...8..497L. doi:10.1038/nnano.2013.100. PMID 23748194. S2CID 5435971.
- ^ Rycerz, A.; Tworzydło, J.; Beenakker, C. W. J. (2007). "Valley filter and valley valve in graphene". Nature Physics. 3 (3): 172–175. arXiv:cond-mat/0608533. Bibcode:2007NatPh...3..172R. doi:10.1038/nphys547. S2CID 119377206.
- ^ a b Cao, T.; Wang, G.; Han, W.; Ye, H.; Zhu, C.; Shi, J.; Niu, Q.; Tan, P.; Wang, E.; Liu, B.; Feng, J. (2012). "Valley-selective circular dichroism of monolayer molybdenum disulphide". Nature Communications. 3 (6): 887. arXiv:1112.4013. Bibcode:2012NatCo...3..887C. doi:10.1038/ncomms1882. PMC 3621397. PMID 22673914.
- ^ a b Mak, K. F.; He, K.; Shan, J.; Heinz, T. F. (2012). "Control of valley polarization in monolayer MoS2 by optical helicity". Nature Nanotechnology. 7 (8): 494–8. arXiv:1205.1822. Bibcode:2012NatNa...7..494M. doi:10.1038/nnano.2012.96. PMID 22706698. S2CID 23248686.
- ^ a b Zeng, H.; Dai, J.; Yao, W.; Xiao, D.; Cui, X. (2012). "Valley polarization in MoS2 monolayers by optical pumping". Nature Nanotechnology. 7 (8): 490–3. arXiv:1202.1592. Bibcode:2012NatNa...7..490Z. doi:10.1038/nnano.2012.95. PMID 22706701. S2CID 13228054.
- ^ Reyes-Retana, J.A.; Cervantes-Sodi, F. (2016). "Spin–orbital effects in metal-dichalcogenide semiconducting monolayers". Scientific Reports. 6: 24093. Bibcode:2016NatSR...624093R. doi:10.1038/srep24093. PMC 4837337. PMID 27094967.
- ^ Sallen, G.; Bouet, L.; Marie, X.; Wang, G.; Zhu, C.R.; Han, W.P.; Lu, P.; Tan, P.H.; Amand, T; Liu, B.L.; Urbaszek, B. (2012). "Robust optical emission polarization in MoS2 monolayers through selective valley excitation". Physical Review B. 86 (8): 3–6. arXiv:1206.5128. Bibcode:2012PhRvB..86h1301S. doi:10.1103/PhysRevB.86.081301. S2CID 62890713.
- ^ Husain, Sajid; Kumar, Abhishek; Kumar, Prabhat; Kumar, Ankit; Barwal, Vineet; Behera, Nilamani; Choudhary, Sudhanshu; Svedlindh, Peter; Chaudhary, Sujeet (2018). "Spin pumping in the Heusler alloy Co2FeAl/MoS2 heterostructure: Ferromagnetic resonance experiment and theory". Physical Review B. 98 (18): 180404. Bibcode:2018PhRvB..98r0404H. doi:10.1103/PhysRevB.98.180404. S2CID 125218447.
- ^ Husain, Sajid; Gupta, Rahul; Kumar, Ankit; Kumar, Prabhat; Behera, Nilamani; Brucas, Rimantas; Chaudhary, Sujeet; Svedlindh, Peter (2020-12-01). "Emergence of spin–orbit torques in 2D transition metal dichalcogenides: A status update". Applied Physics Reviews. 7 (4): 041312. Bibcode:2020ApPRv...7d1312H. doi:10.1063/5.0025318. S2CID 230546779.
- ^ Briggs, Natalie; Subramanian, Shruti; Lin, Zhong; Li, Xufan; Zhang, Xiaotian; Zhang, Kehao; Xiao, Kai; Geohegan, David; Wallace, Robert; Chen, Long-Qing; Terrones, Mauricio; Ebrahimi, Aida; Das, Saptarshi; Redwing, Joan; Hinkle, Christopher; Momeni, Kasra; van Duin, Adri; Crespi, Vin; Kar, Swastik; Robinson, Joshua A. (2019). "A roadmap for electronic grade 2D materials". 2D Materials. 6 (2): 022001. Bibcode:2019TDM.....6b2001B. doi:10.1088/2053-1583/aaf836. OSTI 1503991. S2CID 188118830.
- ^ "2-D materials enhance a 3-D world". phys.org. 2017-01-10.
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